added DHS CISA Known Vulns workflow

[ciberesponce]

New sample: DHS Known Exploited Vulnerabilities

Added DHS Known Exploited Vulns use-case and workflow on top of spotlight APIs

• Documentation
• Code sample

Bandit analysis

[main]  INFO    running on Python 3.8.5
Run started:2022-04-06 16:18:28.010094

Test results:
        No issues identified.

Code scanned:
        Total lines of code: 34522
        Total lines skipped (#nosec): 0

Run metrics:
        Total issues (by severity):
                Undefined: 0
                Low: 0
                Medium: 0
                High: 0
        Total issues (by confidence):
                Undefined: 0
                Low: 0
                Medium: 0
                High: 0
Files skipped (0):

Added features and functionality

• If your PR adds features or functionality, what should be included in the next release notes?

[jshcodes]

Formatting changes and updates to the samples main README will be performed post-merge. These changes will be completed and reviewed as part of the merge to main.